Selective 1H-NMR relaxation investigations of membrane-bound drugs in vitro. 3. Calcium-entry blockers and adenosine.
Selective proton relaxation rates (SPRR) were measured for selected protons of nimodipine or diltiazem in the presence of neutrophils, allowing detection of binding to the cell membrane. Fast exchange exchange of drug molecules between bound and free environments was shown to be the main factor determining the enhancement of SPRR, whereas viscosity effects could be neglected. The SPRR enhancement was almost completely cancelled out by the presence of adenosine as a cosolute in a dose-dependent fashion, leading to the suggestion that the endogenous mediator 'adenosine' affects binding of calcium-entry blockers to the neutrophil surface.
Gaggelli
E
E
Department of Chemistry, University of Siena, Italy.
Di Perri
T
T
Orrico
A
A
Capecchi
P L
PL
Pasini
F L
FL
Valensin
G
G
D000241:Adenosine / Q000737:chemistry*; D002121:Calcium Channel Blockers / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004110:Diltiazem / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D009553:Nimodipine / Q000494:pharmacology
D002121:Calcium Channel Blockers; D009553:Nimodipine; D004110:Diltiazem; D000241:Adenosine